1. Field of the Invention
The present invention relates to a method for limited copying or recording of an information signal such as audio signal, video signal, etc., a system for controlled copying or recording of information signal, using the method, and an information signal recording apparatus also using the method.
2. Description of the Related Art
Recently, as the digital content service by the Internet, compact disc (CD), digital video disc (DVD), etc. has become popular, illegal copying of a digital content has become a serious matter of piracy. To cope with this problem, it has been proposed to add, to a digital content, copy-controlling information used to prevent the digital content from illegally being copied.
The systems having so far been proposed to prevent such illegal copying mainly include a system for disabling copying of any digital content supplied from a specified information source, a system for enabling to copy a digital content once while disabling further copying of the digital content once copied (generation-managing copy control system). The former system is applied for an original software produced and sold by a content maker, such as a digital data recorded in a DVD-ROM. The latter system (generation-managing copy control system) is applied for information to be broadcast in a broadcasting medium, for example.
The generation-managing copy control systems should desirably be able to effectively manage the copy generation. The copy control systems adapted to manage the copy generation include SCMS (Serial Copy Management System) for audio signals, and CGMS (Copy Generation Management System) for video signals.
The SCMS system is such that a copy disable/enable flag transmitted together with a digital audio signal, and a category code indicative of a digital audio source such as a compact disc (CD), digital audio tape (DAT) or the like, are used to provide a serial-copy control for enabling to copy a digital audio signal only once.
More specifically, the SCMS system controls the copy generation of a digital audio signal using SCMS information including a copy disable/enable flag and category code which are transmitted along with the digital audio signal to enable copying of the digital audio signal only at one generation while disabling further copying of the digital audio signal copied at the previous generation.
The CGMS system is such that for transmission of an analog video signal for example, additional information of 2 bits for control of copying are superposed on the analog video signal in a predetermined horizontal zone of the vertical blanking interval thereof, while for transmission of a digital video, additional information of 2 bits for control of copying is added to the digital video data.
The 2-bit information used in the CGMS system (will be referred to as xe2x80x9cCGMS informationxe2x80x9d hereinafter) takes any of the following states:
[00] ....... Copying is enabled.
[10] ....... Copying is enabled for one generation alone.
[11] ....... Copying is disabled.
When the CGMS information added to a video signal takes the status [10], a recording apparatus adopting the CGMS system will decide that the video signal can be copied, and record the video signal which will however have added thereto the CGMS information changed to the status [11] when recorded. When the CGMS information added to a video signal the recording apparatus is going to record is in the state [11], the recording apparatus will be disabled from copying the video signal.
As in the above, the generation-managing copy control systems such as the SCMS and CGMS are adopted to manage the copy generation and enable to copy an information signal such as an audio signal, video signal, etc. only for a private use. Namely, further copying of an information signal once copied can be disabled and thus such a once-copied information signal will not further be copied repeatedly. Therefore, the due profits for the copyrighter of the information signal will not be caused to lessen by any illegal or fraudulent copying of the information signal, and also his or her copyright for the information signal will not be infringed by any such fraudulent copying.
When the SCMS or CGMS system is used to manage the copy generation for copy of an information signal, it is possible to disable further copying into another recording medium of the information signal once copied. Namely, it is disabled to make a second-generation copy from a first-generation copy. However, there is a problem that many copies can be made of the first-generation copy. That is, an original information signal served as recorded in a CD or DVD, for example, from a content maker can be copied limitlessly from the recording media
Also, with use of the so-called high-speed copying technique, an audio or video signal can be copied at a high speed, namely, for a shorter time than the standard reproduction or playing time for the signal. In this case, however, since a desired information signal can be copied for a short time, many copies of the information signal can be made for the first generation even if the SCMS or CGMS system is adopted to manage the copy generation and thus many recording media each having an information signal copied thereto can be produced for a relatively short time. If many copies are made of an information signal using the high-speed copying technique, that is, if recording media each having the information signal copied thereto are illegally produced sold by any other person than the author of the information signal or person entitled to have the copyright of the information signal, the author or the entitled person will lose his or her due profits from the information signal to a large extent.
To avoid the above, a copy limiting system has been proposed which allows each of recording apparatuses to hold identification (ID) information on a copied information signal and disables each recording apparatus from copying any information signal having the same ID information as the ID information already held therein. That is, the copy limiting system enables each recording apparatus to copy each information signal only once.
The copy limiting system disables the recording apparatus from further copying any information signal once copied. Therefore, since the above-mentioned high-speed copying technique cannot be used to make many copies of the same information signal when the copy limiting system is adopted, it is possible to positively prevent any fraudulent copying of an information signal and thus protect the copyrighter""s due profits which would be lost or reduced due to such fraudulent copying of the information signal.
In this case, however, since the once-copied information signal cannot further be copied using the same recording apparatus by which the information signal has been copied once, copying of the information signal within a range of private use will be limited, which will cause the user not to conveniently use the information signal as the case may be.
Also, the copy limiting system enabling to copy the same information signal only once in each of recording apparatuses, makes it necessary to provide in each recording apparatus a memory capable of storing ID information on all copied information signals, and manage all the ID information stored in the memory. Thus, the load to the recording apparatus will be larger.
It is therefore an object of the present invention to overcome the abovementioned drawbacks of the prior art by providing a method for limited recording of an information signal, a system for controlled recording of an information signal, and an information signal recording apparatus, capable of effectively preventing an information signal from fraudulently being copied without impairing the user""s convenience in using the information signal and with no increased load to the recording apparatus.
According to the present invention, there is provided a method for limited recording of an information signal, comprising the steps of:
setting a time;
recording a time-series signal;
measuring an elapsed time from start of the recording step;
comparing the measured elapsed time and the set time with each other; and
limiting the recording step, after completion of the recording, if the comparison result shows that the present time is between the start of the recording step and the set time.
According to the present invention, there will also be provided a method for limited recording of an information signal, comprising the steps of:
setting a time;
reproducing a time-series signal for a standard playing time;
recording the time-series signal;
measuring an elapsed time from start of the recording step;
comparing the measured time and the set time with each other; and
limiting the recording step, after completion of the recording, if the comparison result shows that the present time is between the start of the recording step and the set time.
According to the present invention, there will also be provided a system for controlled recording of an information signal, composed of an information signal output device to provide as an information signal a time-series signal whose information content varies with time, for a time shorter than a standard playing time, and an information signal recording apparatus to record the information signal from the information signal output device, the information signal recording apparatus comprising:
means for measuring an elapsed time from start of the recording; and
a controlling means for comparing a preset time and the measured elapsed time with each other, and limiting the recording, after the information signal has been recorded, if the comparison result shows that the measured elapsed time is shorter than the preset time.
According to the present invention, there will also be provided a system for controlled recording of an information signal, composed of an information signal output device to provide as an information signal a time-series signal recorded in a recording medium, and an information signal recording apparatus to record the information signal from the information signal output device, for a standard playing time of the time-series signal,
the information signal output device providing from the recording medium the information signal and identification information on the information signal; and
the information signal recording apparatus including:
means for receiving the information signal and identification information from the information signal output device;
means for measuring a predetermined elapsed time from start of recording the information signal;
a memory for storing the identification information from the receiving means; and
a controlling means for disabling the information signal recording apparatus from recording the received information signal if the same identification information as already stored in the memory is received within the predetermined elapsed time measured by the time measuring means and after completion of the information signal recording.
According to the present invention, there will also be provided an information signal recording apparatus adapted to receive and record a time-series signal for a time shorter than a standard playing time of the time-series signal, the apparatus comprising:
means for measuring an elapsed time from start of recording the time-series signal; and
means for limiting re-recording of the time-series signal, after the time-series signal has been recorded and for the predetermined elapsed time measured by the time measuring means.
According to the present invention, there will also be provided an information signal recording apparatus adapted to receive an information signal as a time-series signal whose information content varies with time and an identification information on the information signal, and record the information signal for a time equal to a standard playing time of the information signal, the apparatus comprising:
means for detecting the identification information on the information signal;
a memory to hold therein, when recording the information signal, the identification information supplied from the identification information detecting means;
means for measuring, from start of recording the information signal, a sum of a recording time and a predetermined period; and
a recording function controlling means for controlling to disable the recording means from recording an information signal whose identification information is the same as already stored in the memory, after completion of the recording and for the sum of time measured by the time measuring means.
According to the present invention, there will also be provided a recording apparatus comprising:
means for receiving an information signal and a time information on the information signal;
means for recording the information signal;
means for measuring an elapsed time from start of the recording by the recording means; and
means for comparing an elapsed time from start of the recording, set based on the received time information, and the measured elapsed time with each other, and disabling the recording means from recording the same information signal if the measured elapsed time is shorter than the set elapsed time from start of the recording.
According to the present invention, there will also be provided a method for limited recording of an information signal, comprising the steps of:
receiving an information signal and a time information on the information signal;
recording the information signal into a recording medium;
measuring an elapsed time from start of the information signal recording; and
comparing an elapsed time from start of the recording, set based on the time information, and the measured elapsed time with each other, and disabling re-recording of the same information signal into the recording medium if the measured elapsed time is shorter than the set elapsed time from start of the recording.
According to the present invention, there will also be provided a method for limited recording of an information signal, comprising the steps of:
reproducing an information signal from a first recording medium;
recording the reproduced information signal into a second recording medium;
setting time information based on the reproduced information signal;
measuring an elapsed time from start of the recording based on the recording step; and
comparing the measured elapsed time and the set time information with each other, and disabling the recording, after the information signal has been recorded, if the measured elapsed time is shorter than the set time information.
In the present invention, after an information signal is copied by the high-speed copying technique (an information signal is copied for a time shorter than its standard reproduction or playing time for which it is normally reproduced), the recording function is limited for a predetermined period by disabling the high-speed copying, for example, to make it impossible to produce, for a short time, many recording media each having the same information signal copied therein.
Also, in the present invention, after the predetermined time passes, the recording function limitation is canceled and the same recording apparatus is disabled from copying the information signal once copied. Since the information signal can thus be copied for a private use, the user""s convenience in using the information signal will not be impaired.
Also, in the present invention, since even after an information signal is copied by the high-speed copying technique, the limitation of the recording function will not be canceled so long as a time period longer than a time, which would be required to copy the information signal at the normal speed, has not passed, it is possible to positively prevent any fraudulent copying of the information signal, such as many copies of the same information signal made for a short time.
Also, in the present invention, it is disabled to make many copies of the same information signal for a short time. So, it is possible to prevent any fraudulent copying of the information signal, and thus the copyrighter""s due profits from the information will not be caused to lessen by such fraudulent copying.
Also, in the present invention, identification information on an information signal should be held in the recording apparatus for a predetermined period after the information signal is copied. Thus, identification information on copied information signals will not be held limitlessly in the recording apparatus. Therefore, the memory for storage identification information may be a one of not so large a capacity and not so many identification information has to be managed, so that the recording apparatus to record information signals will not be applied with so large a load.
Also, in the present invention, since copying of an information signal is disabled for a predetermined period after the information signal has been copied once, it is possible to make many copies of the same information signal for a short time. Thus, it is possible to prevent the information signal from fraudulently being copied, and so the copyrighter""s due profits from the information signal will not be reduced by such fraudulent copying.
Also, in the present invention, since the recording function limitation is canceled when a predetermined time passes after an information signal is copied and thus the information signal can be copied, it is enabled to copy the information signal for a private use. Therefore, it is possible to prevent any fraudulent copying of an information signal, and so the copyrighter""s due profits from the information signal will not be caused to lessen by such fraudulent copying.
Also, in the present invention, production of many copies of a copy of the same information signal by the same recording apparatus needs a time longer than a time which would be for copying the information signal at the normal speed. So, fraudulent copying of an information signal can positively be prevented.
These objects and other objects, features and advantages of the present intention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings.